The objective of this research program is to elucidate structure-function relationships among a series of pyruvate-specific enzymes which are C-C lyases. There are three general areas of research. 1) Use of the substrate analog bromopyruvate (BrPyv) as a chemical probe of active site fine structure. Among these enzymes, BrPyv serves as a substrate as well as an alkylating agent. Consequently, one can deduce whether alkylation of the BrPyv-sensitive amino acid of the enzyme is a side reaction of kinetically competent complex formation; i.e. whether catalysis and alkylation occur at a single site. This locates the BrPyv-sensitive amino acid in the active site fine structure. Further, among enzymes involving covalent catalysis (e.g. Schiff's base mechanism), BrPyv can crosslink the active site, chemically, by inactivation followed by reduction. 2) BrPyv labeling is being used as a marker for a portion of the active site of 2-keto-3-deoxygluconate-6-P (KDPG) aldolase of p. putida in amino acid sequence studies. This enzyme promises to be the first aldolase visualized through experimentally devising a three-dimensional model showing structural and mechanistic detail. Homologies of active site chemical details at the fine structure and peptide sequences level can then be compared among other pyruvate lyases in further studies. 3) We propose initiating a study of the "enzyme suicide" reaction, the example being the inactivation of microbial citrate lyase by plus allohydroxycitrate. Active site involvement will be demonstrated using kinetic, chemical and stereochemical methodology.